Re: Re: syntax suggestion

David Abrahams wrote:

> Alexander Nasonov <[email protected]> writes:
> 
> 
>>Daniel Wallin wrote:
>>>When in doubt I tend to go for the less verbose and less complicated
>>>alternative, so I guess I like the original version is better:
>>>
>>>     class_<C, bases<A, B> >("C")
>>>       .def(..)
>>>       .def(..)
>>>       ;
>>>
>>>Here are some other possibilities:
>>>
>>>     // Cool, but not very portable
>>>     class_<C(A, B)>("C")
> 
> 
> I like the syntax; I guess we need to decide whether we care about
> older compilers or not.

Yeah, it mirrors both the python and luabind syntax. But I really
dislike dropping older compilers. Maybe supporting both ala
Boost.Function?

>>>       .def(..)
>>>       .def(..)
>>>       ;
>>>
>>>     // Just add more parameters to class_<>, complicates
>>>     // the metaprogramming
> 
> 
> Definitely problematic, especially if you want to be able to pass
> other parameters.

Why? It's not like it's hard to discriminate the params. We do that in
both luabind and BPL already.

    template<class T> void add_base(type<T>, mpl::false_) {}
    template<class T> void add_base(type<T>, mpl::true_)
    {
       ...
    }

    template<class T, class A0, ..., class AN>
    struct class_
    {
        class_(char const*)
        {
            add_base(
                type<A0>(), typename is_base_and_derived<A0, T>::type());
            add_base(
                type<A0>(), typename is_base_and_derived<A1, T>::type());
            ...
            add_base(
                type<AN>(), typename is_base_and_derived<AN, T>::type());
        }
    };

> 
> 
>>>     class_<C, A, B)>("C")
>>>       .def(..)
>>>       .def(..)
>>>       ;
>>>
>>>I'm not sure if either one has any significant benefits from the
>>>original though.
>>>
>>>I think we need more opinions, anyone?
> 
> 
> The only advantage I can see to using the []s is that it becomes a
> bit cleaner to define nested classes.

FWIW, this is what it this currently looks like in luabind:

    module(L)
    [
        class_<X>("X")
            .static_
            [
                class_<Y>("Y")
                   ...
            ]
    ];

-- 
Daniel Wallin


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